Archimedes' screw

Archimedes' screw, a simple mechanical device believed to have been invented by Archimedes in the 3d cent. B.C. It consists of a cylinder inside of which a continuous screw, extending the length of the cylinder, forms a spiral chamber. By placing the lower end in water and revolving the screw, water is raised to the top. The principle is applied in machines used for drainage and irrigation, and also in some types of high-speed tools. It can also be applied for handling light, loose materials such as grain, sand, and ashes.